Chapter 10
Managing Engineering Design
DISCUSSION QUESTIONS
10-1. Q: What are the reasons for dividing the systems engineering/new product development
process into phases or stages?
10-2. Q: How does the design work done in the technical feasibility stage of new product
development differ from that done in the later design stages?
10-3. Q: What are the principal reasons that a configuration control system is necessary?
10-4. Q: For an engineering design or project management system you are familiar with, describe the
drawing release and design review processes.
10-5. Q: Summarize the history of gradually increasing liability of industry for damage caused by
their products.
10-6. Q: What are potential solutions to the liability crisis that haunts American enterprises and
institutions today?
A: The text section on “Reducing Liability” lists 11 types of approaches engineers and
10-7. Q: Select a product line in a specific industry and list actions that can be taken to reduce
product liability.
A: While each answer will be different, a few student responses may serve as examples: (1)
10-8. Q: Identify a company and product (aside from television or automobiles) and tell how good or
poor reliability has significantly affected company success.
10-9. Q: Describe some mechanisms a designer can use to improve maintainability.
A: Increasing reliability increases the MTBF, and designing to minimize the need for
10-10. Q: Give an example of a consumer product with which you are familiar that, through recent
redesign, seems to be a greater value (a better ratio of utility to apparent cost).
A: Compact disc players, VCRs, and quartz watches are examples of products that have
10-11. Q: Discuss how the management functions of planning, organizing, leading, and controlling
relate to the engineering design process.
PROBLEMS
10-1. Q: Given three components, each with a reliability of 0.9, calculate the reliability of a total
system in which the three are arranged (a) three in series, (b) three in parallel, and (c, d) in two
different series/parallel designs each using a total of three components.
A:
10-2. Q: A car contains both hydraulic brakes (reliability 0.95) and mechanical brakes (reliability
0.98). What is the probability of stopping (a) rapidly at high speed, assuming both systems
must work, and (b) at low speed, assuming either system will stop the car?
10-3. Q: An engineered system consists of one each of three components X, Y, and Z with
reliabilities RX, RY, and RZ of 0.94, 0.80, and 0.95 respectively (underlined data omitted in first
printing of the 2nd edition).
(a) What is the system reliability assuming one component of each type must work?
(b) If required system reliability is 0.85, show how you can meet this goal by replacing one of
these components with two of that same component in parallel.
10-4. Q: For a component to which the bathtub curve model of reliability applies, describe the
provisions you would make to assure a low hazard rate in use of the component.
A: The “infant mortality” part of the bathtub curve may be obviated by operating the system
10-5. Q: An engineered system has a hazard rate of 0.01 failure per hour.
(a) What is its MTBF? If the same system has a MTBM of 60 hours, a MDT of 20 hours, and a
MTTR of 6 hours, what is its (b) inherent availability and (c) operational availability?